Describes Mikko Hypponen, chief research officer at anti-virus firm F-Secure, "on Tuesday there were 2."5 million, on Wednesday 3.5 million and today [Friday], eight million.

Mikko Hyppönen of F-Secure, a Finnish internet security company that has been monitoring the attacks, says the best defence is to have strong networks of servers in many countries.

A trio of researchers led by Mikko Myrskyla of the University of Pennsylvania in Philadelphia analysed recent data from most of the world's nations to see if any new trends had emerged.